Mobile communication systems were developed for the purpose of providing mobile users with communication services. With the rapid advance of technologies, the mobile communication systems have evolved to the level capable of providing high speed data communication service beyond the early voice-oriented services.
Recently, standardization for a Long Term Evolution Advanced (LTE-A) system, as one of the next-generation mobile communication systems, is underway in the 3rd Generation Partnership Project (3GPP). The LTE-A system is being developed continuously to improve performance and meet the requirements for high speed packet-based communication at a data rate 3˜10 times higher than the currently available data rate.
In the following, the term “LTE system” is used in the meaning to include the legacy LTE system and the LTE-A system.
With the advance of mobile communication systems, there is an increasing need of a communication method that is efficient in a situation where a certain user uses a plurality of terminals.